1ICU

THE STRUCTURE OF ESCHERICHIA COLI NITROREDUCTASE COMPLEXED WITH NICOTINIC ACID


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.226 

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This is version 1.2 of the entry. See complete history


Literature

The structure of Escherichia coli nitroreductase complexed with nicotinic acid: three crystal forms at 1.7 A, 1.8 A and 2.4 A resolution.

Lovering, A.L.Hyde, E.I.Searle, P.F.White, S.A.

(2001) J Mol Biol 309: 203-213

  • DOI: 10.1006/jmbi.2001.4653
  • Primary Citation of Related Structures:  
    1ICR, 1ICV, 1ICU

  • PubMed Abstract: 
  • Escherichia coli nitroreductase is a flavoprotein that reduces a variety of quinone and nitroaromatic substrates. Its ability to convert relatively non-toxic prodrugs such as CB1954 (5-[aziridin-1-yl]-2,4-dinitrobenzamide) into highly cytotoxic deriv ...

    Escherichia coli nitroreductase is a flavoprotein that reduces a variety of quinone and nitroaromatic substrates. Its ability to convert relatively non-toxic prodrugs such as CB1954 (5-[aziridin-1-yl]-2,4-dinitrobenzamide) into highly cytotoxic derivatives has led to interest in its potential for cancer gene therapy. We have determined the structure of the enzyme bound to a substrate analogue, nicotinic acid, from three crystal forms at resolutions of 1.7 A, 1.8 A and 2.4 A, representing ten non-crystallographically related monomers. The enzyme is dimeric, and has a large hydrophobic core; each half of the molecule consists of a five-stranded beta-sheet surrounded by alpha-helices. Helices F and F protrude from the core region of each monomer. There is an extensive dimer interface, and the 15 C-terminal residues extend around the opposing monomer, contributing the fifth beta-strand. The active sites lie on opposite sides of the molecule, in solvent-exposed clefts at the dimer interface. The FMN forms hydrogen bonds to one monomer and hydrophobic contacts to both; its si face is buried. The nicotinic acid stacks between the re face of the FMN and Phe124 in helix F, with only one hydrogen bond to the protein. If the nicotinamide ring of the coenzyme NAD(P)H were in the same position as that of the nicotinic acid ligand, its C4 atom would be optimally positioned for direct hydride transfer to flavin N5. Comparison of the structure with unliganded flavin reductase and NTR suggests reduced mobility of helices E and F upon ligand binding. Analysis of the structure explains the broad substrate specificity of the enzyme, and provides the basis for rational design of novel prodrugs and for site-directed mutagenesis for improved enzyme activity.


    Organizational Affiliation

    School of Biosciences, University of Birmingham, UK.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
OXYGEN-INSENSITIVE NAD(P)H NITROREDUCTASEABCD217Escherichia coliMutation(s): 0 
Gene Names: nfsB
EC: 1.6.99.7 (PDB Primary Data), 1 (UniProt), 1.5.1.34 (UniProt)
Find proteins for P38489 (Escherichia coli (strain K12))
Explore P38489 
Go to UniProtKB:  P38489
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.226 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 72.01α = 90
b = 57.62β = 103.66
c = 116.98γ = 90
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-04-18
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance